SS 8.3
GD bundled (2.0.28 compatible)
Linux with cPanel
I set the image resize options (Images > Configure).
I made sure the radios were checked to create resized images.
I uploaded an image, and ticked the checkbox to create resized images.
In my edit product info page, I have the pulldown set to use the medium image. When I view my page in a browser, I see the large (original) image.
I've even tried going back to the images page, selecting the image and clicking the Create Resized images button.
No dice.